Foreign Currency Exchange Contracts and Hedging (Narrative) (Details)	1 Months Ended	3 Months Ended	6 Months Ended
	Nov. 09, 2015 USD ($) counterparty	Sep. 30, 2015 USD ($) counterparty	Sep. 30, 2015 USD ($) counterparty	Sep. 30, 2014 USD ($)	Aug. 10, 2015 counterparty	Mar. 31, 2015 USD ($) counterparty
Foreign currency exchange contracts and hedging
Remaining maturity of foreign currency derivatives (in months)			6 months
Number of counterparties in derivative contracts | counterparty		4	4			4
Derivatives designated as cash flow hedges | Foreign currency exchange contracts
Summary of the effect of derivative instruments on the consolidated statements of income
Amount of (loss) gain recognized in OCI on derivatives (effective portion)			$ (1,498,000)	$ 1,625,000
Amount of loss reclassified from accumulated OCI into income (effective portion)			(794,000)	(299,000)
Amount of gain (loss) excluded from effectiveness testing			66,000	(70,000)
Designated as Hedging Instrument | Foreign currency exchange contracts
Foreign currency exchange contracts and hedging
Derivative notional amount		$ 47,000,000	47,000,000			$ 46,000,000
Derivative, Settled During Period, Notional Amount		30,000,000	30,000,000
Non-designated derivatives | Foreign currency exchange contracts
Foreign currency exchange contracts and hedging
Derivative notional amount		8,000,000	8,000,000
Number of counterparties in derivative contracts | counterparty					1
Derivative, entered into and settled during period, notional amount		$ 63,000,000	105,000,000
Summary of the effect of derivative instruments on the consolidated statements of income
Amount of gain (loss) recognized in income on derivatives			$ (461,000)	$ 3,433,000
Subsequent Event | Designated as Hedging Instrument | Foreign currency exchange contracts
Foreign currency exchange contracts and hedging
Remaining maturity of foreign currency derivatives (in months)	18 months
Derivative notional amount	$ 48,000,000
Subsequent Event | Non-designated derivatives | Foreign currency exchange contracts
Foreign currency exchange contracts and hedging
Remaining maturity of foreign currency derivatives (in months)	3 months
Derivative notional amount	$ 83,000,000
Number of counterparties in derivative contracts | counterparty	9